Printed circuit boards (PCBs) are important components in many computing systems. The PCB is often used to mechanically support and connect electronic components that connect to the PCB. The PCB may also provide electrical power to various electronic components that are integral to, or connected to, the PCB.
Many PCBs are made of various flat layers that are sandwiched together. In such multi-layered PCBs, there is usually a ground plane layer and a power plane layer. The ground plane layer is typically a layer of copper and acts as ground for the PCB, providing a reference voltage that is treated as zero volts. The power plane layer is used to provide power, typically direct current (DC) voltage that is used to power circuits mounted on the PCB. Components that need power, or a reference to ground, may connect to one or both of these planes, as necessary.
In the PCBs, the ground plane layer and the power plane layer usually extend out almost to the edges of the PCB. The edges of the ground plane layer and power plane layer are covered with a laminate that prevents the edges from being exposed. However, if the laminate is damaged and the edges of the ground plane layer and the power plane layer are exposed, the integrity of the PCB can be compromised. For example, humidity may create a conductive path between the exposed edge of the ground plane layer and the exposed edge of the power plane layer, resulting in failure. The exposure may result in the growth of conductive anodic filaments (CAFs) between the ground plane layer and the power plane layer, or other problems, which can cause failure. Failure of a PCB can render a system inoperative until the PCB is replaced. As a result, failure of a PCB can be a serious problem.